EspoCRM up to 9.3.3 fromImageUrl isNotInternalHost server-side request forgery

Summaryinfo

A vulnerability, which was classified as critical, was found in EspoCRM up to 9.3.3. This impacts the function HostCheck::isNotInternalHost of the file /api/v1/Attachment/fromImageUrl. Such manipulation leads to server-side request forgery. This vulnerability is uniquely identified as CVE-2026-33534. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in EspoCRM up to 9.3.3. Affected by this issue is the function HostCheck::isNotInternalHost of the file /api/v1/Attachment/fromImageUrl. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality, integrity, and availability. CVE summarizes:

EspoCRM is an open source customer relationship management application. Versions 9.3.3 and below have an authenticated Server-Side Request Forgery (SSRF) vulnerability that allows bypassing the internal-host validation logic by using alternative IPv4 representations such as octal notation (e.g., 0177.0.0.1 instead of 127.0.0.1). This is caused by HostCheck::isNotInternalHost() function relying on PHP's filter_var(..., FILTER_VALIDATE_IP), which does not recognize alternative IP formats, causing the validation to fall through to a DNS lookup that returns no records and incorrectly treats the host as safe, however the cURL subsequently normalizes the address and connects to the loopback destination. Through the confirmed /api/v1/Attachment/fromImageUrl endpoint, an authenticated user can force the server to make requests to loopback-only services and store the fetched response as an attachment. This vulnerability is distinct from CVE-2023-46736 (which involved redirect-based SSRF) and may allow access to internal resources reachable from the application runtime. This issue has been fixed in version 9.3.4.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-33534 since 03/20/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available.

Upgrading to version 9.3.4 eliminates this vulnerability.

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Productinfo

Name

• EspoCRM

Version

• 9.3.0
• 9.3.1
• 9.3.2
• 9.3.3

License

• open-source

Website

• Product: https://github.com/espocrm/espocrm/

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